1. Field of the Invention
This invention relates to a carrier for catalyst and to a method for the production thereof. More particularly, it relates to a method for the production of a carrier for catalyst, which method allows the surface area, pore diameter, and pore volume of the carrier for catalyst, the distributions of magnitudes of these properties, the acidity and basicity of the carrier, and the distributions of magnitudes of these properties to be freely designed to suit variety of reactions for which the catalyst on the produced carrier is intended and to a carrier for catalyst possessing a novel structure.
2. Description of the Prior Art
Porous inorganic carriers have been heretofore produced by preparing as aggregates particulates of a variety of metal oxides such as alumina, silica, titania and zirconia or of refractory materials such as silicon carbide and silicone nitrate, mixing the aggregate with a binding agent comprising a clayish substance as a main component, molding the resultant mixture by pelletization and calcining the molded mixture.
The carriers are produced to provide physical properties such as surface area, pore diameter, and their distributions, which are required for the fulfillment of their role as carrier, for various kind of reactions.
The carrier thus obtained has been finding extensive utility in commercial applications. The catalysts incorporating the carrier of this kind are generally used at relatively high temperatures. During the course of a reaction, the components of the binding agent migrate from the carrier layer to the catalyst layer. These migrating components gradually affect the catalytic activity and selectivity of the catalyst. An alkali metal is used as an additive component of the binding agent, particularly for the purpose of lowering the calcination temperature during the course of production of the carrier. Alkali metals such as sodium, potassium are readily migrating substances. Even when the alkali metal is incorporated only in a minute amount, it produces a serious effect on the quality of the catalyst to be produced. For fear of this adverse effect, it is necessary to produce a highly pure carrier avoiding the use of the binding agent which may well be called an impurity. For example, a method which uses a sol or a salt of the same metal as adopted for aggregate is used as a substitute for the binding agent and a method which resorts to the same treatments of reaction and sintering as in the case of SiC have been known in the art. By reason of restrictions imposed on the process of production, however, the carriers of this class are allowed only narrow ranges for variation of their physical properties and produced carriers are deficient in functionality.
An object of the present invention, therefore, is to provide a novel carrier for catalyst and a method for the production thereof.
Another object of this invention is to provide a carrier without the binding agent of the nature described above and easily permits generous adjustment of physical properties of catalyst to suit a varying reaction for which a catalyst using the carrier is intended.
Still another object of this invention is to provide a method for the production of a carrier, which can be easily carried out more economically.